Book SummaryThe Gene, by Siddhartha Mukherjee

1-Page Summary1-Page Book Summary of The Gene

Scientists have known for centuries that biological traits get passed from one generation to the next, but it was only recently—with a great deal of trial and error, and several technological advancements—that they learned exactly how that happens. The Gene explores key moments in the ongoing study of genetics, with a particular focus on the people behind those moments.

Every part of our bodies, from toenails to hair and everything in between, is built based on the instructions coded into our genes. **Therefore, understanding what genes are and how they work is crucial to understanding our bodies, our health, and even our...

The Gene Summary Part 1: Discovering the Gene

Danish botanist Wilhelm Johannsen coined the word “gene” in 1909, but Mukherjee starts The Gene by talking about three scientists who made crucial strides in the field of genetics before that term even existed: Charles Darwin, Gregor Mendel, and Hugo de Vries.

We’ll begin this guide by discussing the groundwork of genetics those three men laid. Then we’ll discuss what genes are, how they work, and how scientists have learned to understand and manipulate genetic information. We’ll also talk briefly about how our genes impact our personal identities. Finally, we’ll end with Mukherjee’s ideas about the future of genetics, as well as the legal and ethical challenges the field currently faces.

Darwin’s Theory of Evolution

Mukherjee begins the story of genetics in 1859, when Charles Darwin published his theory of evolution, titled On the Origin of Species by Means of Natural Selection (commonly shortened to The Origin of Species). Darwin developed his theory by studying finches in the Galapagos Islands, where he found that birds on different islands had distinctly different beak shapes—for example, one beak type was well suited for cracking open nuts, while...

The Gene Summary Part 2: Chromosomes and DNA

With the foundation of genetics established, Mukherjee moves on to explain how we learned about the biological mechanisms behind inheritance. Namely, he discusses the structures inside of cells that carry genes—called chromosomes—and the actual genetic code found in DNA.

In the early 1910s, geneticist Thomas Morgan bred thousands of fruit flies to study inheritance patterns. He looked for visible traits such as eye color and wing shape, then traced them through numerous generations of fruit flies. Through his observations, Morgan made two crucial discoveries about genes.

The first was what he termed linkage: Morgan noticed that, contrary to Mendel’s Law of Independent Assortment, certain traits were almost always inherited together. He correctly concluded that the genes controlling those traits were somehow physically linked together.

(Shortform note: Specifically, genes are considered linked when they consistently appear together over three or more generations. The odds of the same genes appearing together by chance in almost every individual across three...

The Gene Summary Parts 3 and 4: Writing and Reading Genes

Scientists had discovered that the language of biology is encoded in DNA, and it consists of only four letters. The next step for geneticists was to figure out how to read and write in that language.

Editing Genomes

Mukherjee tells us that, in 1970, Stanford biochemists Paul Berg and David Jackson successfully created recombinant DNA—DNA containing genes from multiple different sources—by inserting the genome of a virus called SV40 into the DNA of a bacteriophage (a type of virus that infects bacteria).

Combining the genomes of two species was an exceptional feat in itself, but it also hinted at a way to quickly and efficiently create drugs such as [restricted term] and certain antibiotics—substances that are normally produced inside of living organisms. For example, inserting an [restricted term]-creating gene into a virus’s genome and allowing that virus to replicate would naturally mean that the [restricted term] gene gets replicated as well. In other words, by editing viruses’ genomes, scientists could turn them into microscopic medicine factories.

(Shortform note: Today, recombinant DNA technology has many uses even outside of medicine, particularly in...

The Gene Summary Part 5: Genetics and Identity

We’ve now had a brief overview of the history of the gene up to the present day. The remainder of this guide will focus on the current state of genetics, how genes impact us personally, and what the future might hold for both the field of genetics and the human race.

As we’ve said, our genes contain the blueprints for our bodies. Therefore, in a very real sense, our genes determine who we are. According to Mukherjee, each of us has crucial elements of who we’ll become—our ability to learn, to use language, and even our physical appearance—encoded in our DNA.

Our Genetic Identities Are Very Similar

Mukherjee says that genetically speaking, humans are all much more similar than we are different. People who believe in significant differences between “races”—for instance, that people of Asian descent are naturally good at math, or that those of African descent are more athletic—are mistaken; there simply isn’t enough genetic variation to account for such differences.

Mukherjee adds that every human alive today can trace his or her lineage down the maternal line to one woman who lived in Africa about 200,000 years ago. The fact that we have a common ancestor,...

The Gene Summary Part 6: Genetic Engineering—the Future of Genetics?

Mukherjee believes we now understand genetics well enough that our next step forward is to start manipulating genes. In this section, we’ll discuss how scientists have already begun to explore the possibilities of gene manipulation with new technologies like stem cell research. However, progress is slow due to ethical and legal concerns, especially when it comes to modifying human genes.

Gene Therapy Could Be the Future of Medicine

Mukherjee says that gene therapy—using genetic engineering to fix damaged or disease-causing genes—offers promising treatments for diseases ranging from hemophilia and cystic fibrosis to cancer.

(Shortform note: Safe and effective gene therapy is still a work in progress. In the US, it’s currently only available to patients who agree to participate in clinical trials.)

One major area of study is in pluripotent stem cells: immature cells that can be genetically manipulated to grow into any type of adult cell. While there are obvious ethical issues with harvesting immature cells from human embryos, doctors now believe it’s possible to manipulate the genomes...

Shortform Exercise: Review What You’ve Learned From The Gene

The Gene contains a lot of information about both the history and science of genetics. Take a moment now to think about what you’ve read, and consider what you know now that you didn’t know before.

What’s something you’ve learned about the history of genetics? This could be an important scientist whose name you didn’t know, or a surprising discovery you weren’t aware of.